Series A3000 Photohelic® Pressure Switch/Gage

3-in-1 Indicating Gage, Lo-limit and Hi-limit Control

Photohelic® Switch/Gages function
as versatile, highly repeatable pressure switches combined with a precise pressure gage employing the time-proven Magnehelic® gage design. The Photohelic® switch/gage measures and controls positive, negative or differential pressures of air and compatible gases. Standard models are rated to 25 psig (1.7 bar) with options to 35 (2.4) or 80 (5.5 bar)
psig. Single pressure 36000S models measure to 6000 psig (413 bar) with a 9000 psig (620 bar) rating. Two phototransistor actuated, DPDT relays are included for low/high limit control. Easy to adjust set point indicators
are controlled by knobs located on the gage face. Individual set point deadband is one
pointer width - less than 1% of full scale. Set points can be interlocked to provide
variable deadband - ideal for control of fans, dampers, etc. Gage reading is continuous and unaffected by switch operation, even during loss of electrical power. Choose from full scale pressure ranges from a low 0-.25" (0-6 mm) w.c. up to 30 psi (21 bar); single positive pressure to 6000 psig (413 bar).

Photohelic Sensing - How It Works
In typical applications, these Dwyer switch/gages control between high and low pressure set points. When pressure changes, reaching either set point pressure, the infrared light to the limiting phototransistor is cut off by the helix-driven light shutter. The resulting phototransistor signal is electronically
amplified to actuate its DPDT slave relay and switching occurs. Dead band between make and break is 1% of full scale or less - just enough to assure positive, chatter-free operation.

Options

High & Low Latching Circuits. Dwyer Photohelic® switch/gages can be wired for high-latching, low-latching or
combination high-low latching circuits. That is, the equipment will
hold in these respective positions once activated and until manually reset.
This can
be particularly useful for alarm and signal applications where control is accomplished
by another Photohelic® switch/gage or other means. Complete
wiring and operational instructions are included. Where manual reset is required
a dry
circuit push button such as Dwyer
Part A-601 should be used.

-SR Single contact, right set point, for actuation on increasing
or decreasing pressure.

-OLS OEM Model, less relay and transformer components and housing
but including infared diodes and phototransistor(s), light shutter and
set pointer(s). For single or double contact.